Multiple Abnormal Grain Growth Phenomena in Nanocrystalline Pure Nickel Produced by Electrodeposition

摘要

Here we show multiple abnormal grain growth phenomena in nanocrystalline pure Ni with temperature change, based on the microstructural analysis. Abnormally large grains are observed in the nanocrystalline Ni thermally exposed in air for 1 hr at 200 deg C, 500 deg C, and 800 deg C, respectively. Such large grains formed at 500 deg C for 1 hr having facet grain boundary structure, show kinetically fast growth rate rather than others exposed to 200 deg C and 800 deg C for the same time period. The facet grain boundary appears to be related to the abnormal grain growth rate, suppressing the fine matrix grain growth. The mechanism underlying abnormal grain growth is examined for each temperature range.